An optically active amino acid, particularly an optically active unnatural amino acid which does not exist in nature, is an important constituent factor for a pharmaceutical product, an agricultural agent, a chemical product or the like. With respect to an optically active imidazolidinone derivative as a chiral glycine synthon developed for synthesizing such an unnatural amino acid, following synthetic methods are conventionally known.                i) A method of synthesizing the derivative from a glycinamide derivative and pivalaldehyde (Non-patent Document 1)        ii) A method of synthesizing the derivative from an optically active serinamide derivative and pivalaldehyde (Non-patent Document 2)        iii) A method of synthesizing the derivative from an optically active methioninamide derivative and pivalaldehyde (Non-patent Document 3)        iv) A method of synthesizing the derivative from a chiral glycinamide derivative and pivalaldehyde (Non-patent Document 4)        
However, the method i) is difficult to be industrially carried out, since a salt production and salt dissolution process is inevitably required in the method i) in which the produced optical isomers are resolved as mandelate salts thereof. Further, the method ii) is also difficult to be industrially carried out, since in the method ii) an optically active serine is used and it is necessary to oxidize and decarbonate the hydroxymethyl group thereof after forming an imidazolidinone ring. Furthermore, the method iii) is also difficult to be industrially carried out, since cumbersome procedures are required for the method iii) because of a plurality of induction processes from optically active methionine similarly to the case of ii). In the case of the method iv), since optically active glycinamide is used, the produced imidazolidinone derivatives are obtained as an isomeric mixture. Accordingly, the method iv) is similarly difficult to be industrially carried out, since it is required to purify the isomeric mixture by a silica gel column to obtain a pure single isomer. In addition, pivalaldehyde used in common for the methods i) to iv) is an expensive compound and use of the compound in industrial scale is not preferred.
Non-patent Document 1: Angew. Chem. Int. Ed., 1986, 345
Non-patent Document 2: Helv. Chim. Acta., 1985, 68, 949
Non-patent Document 3: Modern Synthetic Methods, 1986, 4, 128
Non-patent Document 4: J. Org. Chem., 1995, 60, 6408